Among the comments registered in the moments after: “i can't even begin to imagine what this Tupac hologram is doing to all the people at Coachella that have been on acid for 3 days straight,” wrote @JordanETID

Tweeted @KirillWasHere: "Next year Coachella should just have a HOLOGRAM TENT featuring all the acts that we wish we got to see live...," while @Swagstro offered this thought: "I wonder how many rappers retired from seeing the Tupac hologram on COACHELLA."

Still, some in the crowd found it unsettling. "Was completely freaked out by the Tupac hologram and I'm fairly certain I was one of five people out of 100,000 not on drugs," tweeted @molly_knight.

To clarify the Tupac "hologram" -- remember that true holograms don't exist yet at that size, resolution, or in full-color. It was done with an old magic gag dating back to the 1800s called "Pepper's Ghost," which uses a flat glass reflection to create a "dimensional" image in space.

Tupac was created by a company called Musion Eyeliner, whose version of Pepper's Ghost is accomplished with lightweight mylar film instead of glass, making the effect "tour-able".

Hatsune Miku!!! They're a live band from Japan with an Anime character hologram as their lead; they been touring with the tech as far back as 2009. The live performance videos posted at Youtube are pretty impressive!